Many mechanical and electronic devices or equipment require a user to interact with the device by depressing keys on a keyboard, such as a computer keyboard or musical keyboard, or other such pressure sensitive devices. Keyboards or other pressure sensitive devices including equipment or machinery operator controllers are often marked with visual indicia to allow a user to know which key must be depressed. Such indicia, however, is not recognizable by a visually impaired individual, and accordingly, the devices are not adapted for use by a visually impaired individual. Thus, using or educating for use of devices such as computer keyboards, musical keyboards and other button operated equipment, devices or machinery by visually impaired individuals is difficult and may even be impossible.
Devices exist for teaching or communicating a symbolic tactile recognition language, such as Braille. For example, U.S. Pat. No. 4,880,384 by the inventor of the present invention shows such a device with blocks having a Braille character which may be interchangeably arranged and fixed to a board to form words and sentences. However, this apparatus is not adapted to be used with a keyboard or other such pressure sensitive device because the individual blocks and rigid board may not be easily mounted to a such a device.
Accordingly, what is needed is an interchangeable overlay system which covers a keyboard or other similar pressure sensitive device and which is made of a flexible material to allow for depressing of keys on the keyboard. Further, the overlay should be adapted to removably engage with blocks having a character which is recognized by touch, such as a Braille character, and recognized visually, so that the keyboard can be interchangeably adapted for interaction with a visually impaired individual. Both the overlay and the individual block should be easily mountable and removable for increased flexibility in adapting the keyboard for use by visually impaired individuals.